Vacuum cleaner having a divergent diffuser



Jan. 30, 1968 F. K. BAYLESS VACUUM CLEANER HAVING A DIVERGENT DIFFUSER 4Sheets-Sheet 1 Filed Feb. 9, 1967 INVENTOR. FRANK K. BAYLESS W HISATTORNEYS Jan. 30, 1968 F. K. BAYLESS VACUUM CLEANER HAVING A DIVERGENTDIFFUSER 4 Sheets-Sheet 2 Filed Feb. 9, 1967 FIG. 4

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INVENTOR. FRANK K. BAY LESS I%W M I HIS ATTORNEYS Jan. 30, 1968 F. K.BAYLESS VACUUM CLEANER HAVING A DIVEHGENT DIFFUSER 4 Sheets-Sheet sFiled Feb.

INVENTOR. FRANK K. BAY LESS ms ATTORNEYS Jan. 30, 1968 F. K. BAYLESSVACUUM CLEANER HAVING A DIVERG ENT DIFFUSER 4 Sheets-Sheet 4 Filed Feb.9, 1967 INVENTOR.

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S 5 s W a E L N Yaw R A O B A K N A E /M H Y A wL E F 0 n N mu. N U N RW M 0 M LFI FOT United States Patent O 3,366,316 VACUUM CLEANER HAVING ADIVERGENT DIFFUSER Frank K. Bayless, Darien, Conn., assignor toElectrolux Corporation, Old Greenwich, Conn., a corporation of DelawareContinuation-impart of application Ser. No. 451,535, Apr. 28, 1965. Thisapplication Feb. 9, 1967, Ser. No. 614,934

4 Claims. (Cl. 230-117) ABSTRACT OF THE DISCLOSURE In a vacuum cleanerairflow is provided by a motor-fan unit within the body of the cleaner.The air being discharged from the motor-fan unit is directed into anannular diverging space defined by wall members which surround the laststage of the blower. The air from the blower is introduced into thediffuser space at its smaller cross-section and is discharged from theenlarged end of the diffuser for increased fan efliciency or increasedairflow and suction.

Related application This application is a continuation-in-part ofcopending application Ser. No. 451,535 by the inventor hereof, nowPatent No. 3,303,996 dated Feb. 14, 1967.

Background of the invention Vacuum Cleaners having motor-fan units areknown and with a given unit a certain airflow or suction is produced.This invention relates to the discovery that the airflow or suction of agiven motor-fan unit is increased by a diverging diffuser.

Air diffusers are known in the prior art in connection with compressorssuch as disclosed in British Patent 701,560 of Dec. 30, 1953. In thispatent primary and secondary diffusers are used in series to reduce theoverall frontal area of the compressor. However, no prior art is knownin which a diverging diffuser in combination with a motor-fan unit in avacuum cleaner is used for increasing suction, or negative pressure in avacuum cleaner.

Summary of the invention The primary object of the invention is toimprove the cleaning performance of a vacuum cleaner by the use of adiverging diffuser.

Another object of the invention is to improve the cleaning performanceof a vacuum cleaner by an economical and simple change in constructionof the cleaner.

Brief description of drawing FIG. 1 is a longitudinal, cross-section,showing a reverse-flow motor-fan unit situated in the tank unit of avacuum cleaner and incorporating one embodiment of the diffuseraccording to my invention;

FIG. 2 is a somewhat partial section of FIG. 1 showing my diffuser ingreater detail;

FIG. 3 is a somewhat diagrammatic view of my diffuser showing variousgeometrical relationships thereof and a somewhat idealizedrepresentation of the airflow therethrough.

FIG. 4 is a diagrammatic view similar to FIG. 3 but showing a section ofmy diffuser as being straight, rather than arcuate, so that the variousgeometrical relationships thereof and the idealized airflowrepresentation may be more clearly shown for purposes of explanation;

FIG. 5 is a partial longitudinal cross-section similar to that shown inFIG. 1, but showing an embodiment of my diffuser incorporated in acommercial vacuum cleaner having a separately cooled motor so that itcan be used for picking up water;

FIG. 6 is a partial cross-section view as viewed along the line 66 inFIG. 5;

FIG. 7 is a graphical representation showing the air performance of areverse-flow motor-fan unit having a diffuser according to my invention;and

FIG. 8 is another graphical representation showing the electricalperformance of the reverse-flow motor-fan unit having a diffuseraccording to my invention.

Description 0 preferred embodiments In FIG. 1 a motor-fan unit having adiffuser according to the first embodiment of my invention is shownmounted within a tank 10 of a tank-type or canister-type vacuum cleaner,the unit being of the reverse fiow type. A dust bag compartment 12having a plurality of holes 13 therethrough is also mounted within thetank 10 and a dust bag 14 is situated in the compartment 12.

The motor-fan unit is comprised of an electric motor 16 and acentrifugal fan 18 which is driven by the motor. The motor and fan arelocated downstream of the dust bag 14 so that filtered airstreams,indicated by the arrows A, emanating from the dust bag can pass over themotor 16 to cool it before the airstreams enter the fan 18.

The motor 16 may be a conventional series wound universal motorincluding a wound armature 20 on an armature shaft 21 which is journaledfor rotation in the two bearing members 22 and 23. Surrounding thearmature 20 is a laminated stator 19 which includes two opposing polepieces 24. A field winding 25 encompasses each pole piece 24. One end ofthe armature shaft 21 is provided with a commutator 26 which iselectrically energized through a pair of carbon brush units 17. Themotor 16 also includes two stationary support frames 27 and 28 which.when coupled together by means of bolts 29 support the stator 19 andarmature 20. The support frame 27 includes ribs 30 between which thereare defined openings so that the airstreams A can pass over the variousparts of the motor to cool it. As indicated, the airstreams A pass overthe armature 20, stator 19 and field winding 25. In addition, thesupport frame 27 serves as a support for the bearing member 23 and forthe brush units 17. The support member 28 has a cup-like housing and isopen at one end, the other end thereof being partly closed and carriesthe bearing member 22. At the partly closed end of the support frame 28there is formed a number of radial spokes 31, or rib members and betweenthese adjacent spokes 31 openings are provided so that airstreams A canpass through, as indicated in FIG. 1, into the fan unit 18. Supportframes 27 and 28 may be fashioned from aluminum or the like; forexample, cast aluminum is one of a number of materials which aresuitable.

Fastened by means of rivets 32 to the outside surface of support frame28 at the partly closed end thereof is a stationary cup-like housing 33which may also be fashioned from aluminum. At one end of this housing 33there is formed an outwardly turned annular flange 34 and in about threeor four places on this flange there are provided large diameter holes35, through which bolts 36, pass for the purpose of securing the housing33 to a bulkhead 37, which bulkhead is secured to the inside surface ofthe tank 10, as by welding. An annular rubber gasket 38 is also providedto help secure these aforementioned members together so that vibrationsmay be damped. In the center of the partly closed end of the ing race39. Secured to the support frame 28 by means of screws (not shown) arethe two centrally apertured sta tionary bearing shields 42 and 43. AsshoWn the diameter of the central aperture of these shields 42 and 43 issufficiently large so that the shields will not interfere with rotationof the armature shaft 21 or with any of the other elements, hereinafteridentified, which rotate together with the armature shaft 21. The spacesbetween the two bearing races 39 and 41 and between the two shields 42and 43 are filled with a suitable lubricant.

Fitted over the outside surface of the housing 33 and fastened theretois another stationary cup-like housing 44. The housing 44 which may beformed from sheet aluminum or the like extends for a substantialdistance in an axial direction beyond the end of the housing 33. Withinthe space defined between the outer end wall of housing 33 and theinterior end wall of the housing 44 there is located a first stagecentrifugal impeller 45 and a first stage stationary diffuser 46.

At one end of the cup-like housing 44 there is provided an opening 47through which airstreams A can flow into a second or final stagecentrifugal impeller 48. Within the cup-like housing 44 and arrangedparallel to an inside wall surface thereof there is a centrallyapertured oircular disc 49. Between the housing 44 and the disc 49 thereis situated a plurality of spaced-part spiral-like vanes 50. The vanes50 are radially arranged in the space between a wall of housing 44 andthe disc 49. Each vane 50 has projecting ears such as the ear 51. Theseears 51 extend through accommodating holes in the housing 44 and in thedisc 49 and are bent over onto the outside surfaces of the housing andthe disc. To ensure a positive connection to the housing 44 and to thedisc 49 the bent over ears 51 of the vanes 50 may be spot weldedthereto. As may be seen in FIG. 1 the central aperture in the disc 49.has a diameter large enough to allow the armature shaft 21 and the otherelements coupled therewith to rotate freely without interfering with thedisc 49. Thus, the first stage difiuser 46 is comprised of thestationary end wall of housing 44, the disc 49 and the vanes 50 situatedtherebetween.

T-he first stage centrifugal impeller 45 is located between the wallmember 33 and the stationary difi'user 46, as shown in FIG. 1. Theimpeller 45 is comprised of two spaced-apart circular discs 52 and 53and spiral-like radially arranged vanes 54 connected therebetween. Eachvane 54 includes a plurality of ears,-such as the ear 55, which protrudethrough accommodating holes in the discs 52 and 53. These ears 55 arebent over and may be spot welded to the outside surfaces of the discs.As shown, the disc 52 has a large diameter central aperture 56 whichadmits airstreams A into the impeller 45.

The second or last stage impeller 48 is comprised of two spaced-apartcircular discs 57 and 58 and radially arranged spiral-like vanes 59connected therebetween. These vanes 59 are regularly spaced-apartbetween the discs '57 and 58 and each vane includes a plurality of ears60 which protrude through accommodating holes in the discs 57. and 58and are bent over and may be spot welded to the outside surfaces ofthese discs. As shown the disc 57 has a large diameter central aperture61 to admit airstreams A into the final stage impeller 48.

The armature shaft 21 has an enlarged section 62 having a diametergreater than the remainder of the shaft 21. At the juncture of theenlarged section 62 and the smaller diameter portion of the armatureshaft there'is defined an annular shoulder 63 against which one end ofthe inner bearing race 39 is in contact and situated next to theopposite end of the bearing race 39 is a flanged cylindrical body 64.One end of this body 64 is in contact with the, end of the bearing 39and the flanged portion therewith is a centrally apertured cylindrical.body 66 which also encompasses the armature shaft 21. Situated betweenthe opposite end of the cylindrical body 66 and the face of the disc 58is another centrally apertured washer 67 which also encompasses theshaft 21. In contact with the opposite face of disc 58 is anothercentrally apertured Washer 68 which also encompasses the armature shaft21. The end of the armature shaft 21 is externally threaded and itreceives an internally threaded nut '69 which is tightened so as to bearwith considerable force against the face of the washer 68. The forceexerted by nut 69 is transmitted to the annular shoulder 63 through thewasher 68, disc 58, washer 67, cylindrical body 66, washer 65, disc 53,flanged body 64 and the inner bearing race 39. Thus, all of theaforementioned part-s between the shoulder 63 and the nut 69 andincluding the nut 69 rotate together with the armature shaft 21 due tothe high pressure contact therebetween. Also since the discs 52 and 57are rigidly secured to the discs 53 and 58 through the vanes 54 and 59respectively in the manner hereinbefore set forth, the first and secondstage impellers 45 and 48 defined by these vanes and discs rotatetogether with the armature shaft 21.

A dish-like wall or cup member 70 formed in a somewhat frusto-conicalshape from suitable sheet metal, such as aluminum, is secured to theoutside of the housing 44 by means of the evenly spaced brackets 71 andthe sheet metal screws 72. The mounting brackets 71 are spot welded tothe inside surface of the wall member 70 and the sheet metal screws 72are threaded through the brackets 71 and the walls of the housings 33and 44, as indicated at FIG. 1, so that the wall member 70 is maintainedin a spaced relationship relative to the housing 44.

As shown in FIGS. 2 and 3 the volumetric space between the tip of thefinal stage impeller wheel 48 and the inside surface of the wall member70 which is above the tip of the wheel 48 is somewhat annular. Thisspace wouldv be perfectly annular except for the curvature of thatportion of the wall member 7 0 which is above the tip of the impellerwheel 48. Contiguous with the aforesaid annular space and extendingaxially therefrom is the annular frusto-conical diffuser space extendslongitudinally from the line L1 to the line L2 (see FIG. 2), and isbounded by the inside surface of the wall member 70 and the outsidesurface of the housing 44. As shown in FIG. 2 the Wall member 70 isoutwardly flared at an angle B relative to the wall surface of thehousing 44.

Tests, hereinafter discussed in detail with reference to FIGS. 7 and 8,were conducted to determine relative performance of a reverse-flowmotor-fan unit having, in accordance with my invention, an annularfrusto-conical diffuser and a like motor-fan unit having a conventionalprior art annular cylindrical difiuser. These tests showed that themotor-fan unit incorporating the aforesaid annular frusto-conicaldiffuser produced a higher suction or vacuum over its entire airflowrange than the comparable motor-fan unit employing the conventionalprior art diffuser.

While it is not fully understood why the motor-fan unit employing myannular frusto-conical diffuser performs better than the prior artmotor-fan units the following explanation, based on FIGS. 3 and 4, seemsto account for the improved performance. However, I do not wish to bebound by such explanation.

In FIGS. 3 and 4 there exists the following relationship between theangles B, C and D.

tan DSin C-tan B In the above equation B is the angle at which the wallmember 70 is disposed relative to the housing 44 (see FIG. 2). C is'theangle at which the airstreams A exit into the diifuser space which isdefined between the wall member 70 and the housing 44. The angle C wasmeasured by observing the position which a thread assumed when it wasinserted into the annular space above the tip of the final stageimpeller wheel 48. The'angle D, which is calculated from the aboveequation, is the diverging angle at which it is believed the airstreamsA difiuse into the annular frusto-conical diffuser space.

In one illustrative embodiment of my invention the ang e B was set at 17and the angle C was measured with the aid of a thread to be 20. Theangle D was calculated to be 6. For air a diffusion angle of between 6and 8 is considered to be the range which permits the air to diffusewith the least loss of energy. Thus it seems plausible that the reasonfor the improved performance of a fan unit embodying my annularfrusto-conical diffuser is that airstreams can seek an effectivediffusion angle of between 6 and 8 which diffusion angle permits the airto convert its velocity energy into pressure energy with the leastenergy loss.

Another embodiment of my invention is shown in FIGS. 5 and 6. Themotor-fan unit shown in these figures is similar to the motor-fan unitshown at FIGS. 1 and 2 so that no further description is necessary, butin FIGS. 5 and 6 a separate airflow is provided for cooling the motor 16by virute of a bladed fan 110 fixed on the motor shaft at the end remotefrom the centrifugal fan 18. The motor 16 is enclosed within a separatecompartment 111 defined by a cylindrical wall 106 and the impervious orcontinuous base portion 109 of the motor frame. The cylindrical wallmember 106 is snugly fitted onto the frame 108 and terminates short ofthe series of opening 104 between the frame portions 108 and 109.Cooling air for the motor is drawn into the compartment 111 by the fan110 through a plurality of openings 102 communicating with the shroud103 concentrically surrounding the fan 110. This air passes through theopen portion of the motor frame, over the motor and exits fromcompartment 111 through the openings 104 which communicate with channel105 defined by wall 107. Air recirculation between channel 105 and theshroud 103 is prevented by an O-ring 112 as shown in FIG. 5. The coolingair is discharged to atmosphere through suitable openings 113 in thehousing 101. Of course the channel 105 may extend radially so that airis discharged from the compartment 111 radially rather than axially asshown.

In the embodiment according to FIG. 5 airflow through the fan 18 passesinto the diffuser 170 formed integral with the motor frame. The diffuser170 is identical with the diffuser 70 of FIG. 1 except that air passesthrough the diffuser in the same axial direction as the airflow throughthe fan 18. Air discharged from the diffuser 170 enters the relativelylarge space 120 within the dome 101 and passes to atmosphere through abaffied aperture 121. Radially extending air guide vane 173 may beconnected with the wall 106 in any suitable manner such as by welding.The vanes 173 extend into the space 120 and are evenly spaced from oneanother and may extend across the space 120 up to the wall 101.

Three reverse flow motor-fan units were tested and the tests appear ingraphic form in FIGS. 7 and 8. Motorfan unit I was provided with aconventional vaneless annular cylindrical diffuser wherein the wallmember 70 was maintained parallel to the housing 44 rather than disposedat the angle B as shown in FIG. 2. Motor-fan unit II was provided withan annular frusto-conical difi'user of the kind shown in FIGS. 1 and 2.Motor-fan unit 111 was provided with the annular frusto-conical diffuserand the vanes 73 as shown in FIGS. 5 and 6. In each of the threemotor-fan units the diameter of the fan housing 44 was approximately 5.3inches. The diameter of the impeller wheels are approximately 4.9 inchesand each impeller wheel had an axial length of about 0.3 inch. Inmotor-fan unit I a constant distance of approximately 0.120 inch wasmaintained between the wall member 70 and the housing 44. In motor-fanunits 11 and III the throat dimension T indicated in FIG. 2 wasmaintained at 0.120

6 inch. In motor-fan units II and III the angle B of the wall member 70relative to the housing 44 was maintained at 17.

A comparison of the motor-fan units II and III with the motor-fan unit Iin FIG. 7 shows that the motor-fan units II and III provided a highersuction over the entire airflow range as compared with the suctionproduced by motor-fan unit 1, Further, motor-fan unit 111 produced aneven higher suction over its entire airflow range than motor-fan unitII. Moreover, as appears in FIG. 8 the higher suction produced bymotor-fan units II and III was achieved at but a relativelyinsignificant increase in input power.

While I have disclosed two more or less specific embodiments of myinvention it is to be understood that this has been done for purposes ofillustration only. Also, although I have shown my invention inconnection with reverse-flow motor blower units, it is equallyapplicable to direct-flow blowers and to blowers having separate coolingof the motor, and the scope of my invention is to be limited only by theappended claims.

What is claimed is:

1. A vacuum cleaner comprising a tank member having openings at eachend, dust collecting means communicating with one of said openings forseparating entrained solids, a motor-fan unit within said tank fordrawing air into said One opening and discharging this air from theother of said openings, said motor-fan unit including a multi-stagecentrifugal impeller means including at least one impeller dischargingair at its periphery, means defining a diverging diffuser space incommunication with said one impeller for receiving the discharging airtherefrom at the smaller area of said diverging diffuser, a seconddiffuser space within said tank adjacent the other of said openings forreceiving air from said diverging diffuser, means defining a discretecompartment enclosing the motor of said motor-fan unit, separate meansfor communicating said compartment with ambient atmosphere, and separatefan means within said compartment for circulating cooling air over saidmotor; said means defining a discrete compartment enclosing said motorcomprises a generally cup-shaped shroud connected to the motor frame,wall means forming a channel in said shroud, said channel being open ateach longitudinal end, an aperture in said motor frame communicatingwith one end of said channel and the other end of said channel openingto atmosphere at the end of said tank having said other opening.

2. A vacuum cleaner according to claim 1 with the addition of air guidemeans in at least one of said diffuser spaces.

3. A vacuum cleaner according to claim 1 wherein the angle of saiddiverging diffuser space is substantially 17 degrees.

4. A vacuum cleaner according to claim 1 wherein said means forcommunicating said compartment with ambient atmosphere includes meansdefining a channel connected with said compartment remote from saidseparate fan means,

References Cited UNITED STATES PATENTS 2,021,298 11/1935 Forsberg230--117 2,534,808 12/1950 Bevington et al 230117 2,898,031 8/ 1959Voigt 230-127 2,336,716 12/ 1943 Clements 2301 17 FOREIGN PATENTS266,219 2/ 1927 Great Britain.

282,797 10/ 1928 Great Britain.

611,870 10/ 1960 Italy.

HENRY F. RADUAZO, Primary Examiner.

